rom/exec/wait.c

   1 /*
   2     Copyright © 1995-2010, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Wait for some signal.
   6     Lang: english
   7 */
   8 #define DEBUG 0
   9
  10 #include <aros/debug.h>
  11 #include <exec/execbase.h>
  12 #include <aros/libcall.h>
  13 #include <proto/exec.h>
  14 #include <proto/kernel.h>
  15
  16 #include "exec_intern.h"
  17
  18 /*****************************************************************************
  19
  20     NAME */
  21
  22         AROS_LH1(ULONG, Wait,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(ULONG, signalSet, D0),
  26
  27 /*  LOCATION */
  28         struct ExecBase *, SysBase, 53, Exec)
  29
  30 /*  FUNCTION
  31         Wait until some signals are sent to the current task. If any signal
  32         of the specified set is already set when entering this function it
  33         returns immediately. Since almost any event in the OS can send a
  34         signal to your task if you specify it to do so signals are a very
  35         powerful mechanism.
  36
  37     INPUTS
  38         signalSet - The set of signals to wait for.
  39
  40     RESULT
  41         The set of active signals.
  42
  43     NOTES
  44         Naturally it's not allowed to wait in supervisor mode.
  45
  46         Calling Wait() breaks an active Disable() or Forbid().
  47
  48     EXAMPLE
  49
  50     BUGS
  51
  52     SEE ALSO
  53         Signal(), SetSignal(), AllocSignal(), FreeSignal()
  54
  55     INTERNALS
  56
  57     HISTORY
  58
  59 ******************************************************************************/
  60 {
  61     AROS_LIBFUNC_INIT
  62
  63     ULONG rcvd;
  64     struct Task *me;
  65
  66     /* Get pointer to current task - I'll need it very often */
  67     me = FindTask (NULL);
  68
  69     D(bug("[Exec] Wait(0x%08lX) called by %s\n", signalSet, me->tc_Node.ln_Name));
  70     /* Protect the task lists against access by other tasks. */
  71     Disable();
  72
  73     /* If at least one of the signals is already set do not wait. */
  74     while(!(me->tc_SigRecvd&signalSet))
  75     {
  76         D(bug("[Exec] Signals are not set, putting the task to sleep\n"));
  77         /* Set the wait signal mask */
  78         me->tc_SigWait=signalSet;
  79
  80         /*
  81             Clear TDNestCnt (because Switch() will not care about it),
  82             but memorize it first. IDNestCnt is handled by Switch().
  83         */
  84         me->tc_TDNestCnt=SysBase->TDNestCnt;
  85         SysBase->TDNestCnt=-1;
  86
  87         /* Move current task to the waiting list. */
  88         me->tc_State=TS_WAIT;
  89         Enqueue(&SysBase->TaskWait,&me->tc_Node);
  90
  91         /* And switch to the next ready task. */
  92         KrnSwitch();
  93
  94         /*
  95             OK. Somebody awakened me. This means that either the
  96             signals are there or it's just a finished task exception.
  97             Test again to be sure (see above).
  98         */
  99
 100         /* Restore TDNestCnt. */
 101         SysBase->TDNestCnt=me->tc_TDNestCnt;
 102     }
 103     /* Get active signals. */
 104     rcvd=me->tc_SigRecvd&signalSet;
 105
 106     /* And clear them. */
 107     me->tc_SigRecvd&=~signalSet;
 108
 109     /* All done. */
 110     Enable();
 111
 112     return rcvd;
 113
 114     AROS_LIBFUNC_EXIT
 115 }
 116